Escherichia coli (hereinafter referred to as ‘E. coli’) is a Gram-negative, short rod-shaped bacterium belonging to the genus Escherichia and the family Enterobacteriaceae, and is one of the normal flora existing in the intestines of various animals including mammals. It was known that most of the strains of E. coli are non-pathogenic and may cause opportunistic infections, but some highly pathogenic strains cause diverse intestinal diseases and septicemia in animals including humans.
It was known that among these E. coli strains, particularly, avian pathogenic E. coli (APEC), which is E. coli infected through respiratory tract of birds, for example, chickens, ducks, turkeys, or the like, infiltrates into the body through respiratory mucosa. APEC causes various diseases such as septicemia, granuloma, airsacculitis, salpingitis, arthritis, or the like, in birds. Particularly, APEC causes significant economic damage to a poultry industry in that APEC causes respiratory diseases mainly in poultry, or the like, such that APEC becomes a problem.
Meanwhile, bacteriophage is a specialized type of virus that infects and destroys only bacteria, and can self-replicate only inside host bacteria. The bacteriophage has strong host specificity as compared to antibiotics, and recently, a problem of emergence of resistant bacteria against use of antibiotics has been serious, such that an interest in practical use of the bacteriophage has increased (Non-Patent Documents 1 and 2).
Therefore, research regarding the bacteriophage has been actively conducted in many countries around the world, and in addition to a patent application for bacteriophage, an attempt to acquire Food and Drug Administration (FDA) approval for a composition containing the bacteriophage has been gradually increased.
As the prior art for the bacteriophage, 7 kinds of bacteriophages for controlling E. coli 0157:H have been disclosed in Patent Document 1, and a bacteriophage having a specific bacteriocidal activity against Staphylococcus aureus has been disclosed in Patent Document 2. Further, lytic protein derived from a bacteriophage specifically destroying a peptidoglycan structure of bacterial cell membrane, and bacteria lysates by the lytic protein have been disclosed in Patent Document 3.
However, in spite of presence of the following prior arts, a technology associated with the bacteriophage for preventing and/or treating infectious diseases by APEC, which is an important problem in breeding birds including poultry, is still insufficient, such that a bacteriophage and a technology associated with the bacteriophage should be developed.